Investigations of cattle grazing behavior and effects of the red imported fire ant

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The purpose of this research was to study the effects of the Solenopsis invicta Buren; Hymenoptera: Formicidae, the red imported fire ant (RIFA) on Texas livestock and was funded by the Texas Fire Ant Initiative. This research was multipurpose in nature, and several different aspects of RIFA and their effects on livestock were studied. Additionally a Global Positioning System (GPS) was designed and fabricated in order to conduct a portion of the research.
The initial phase of this research was to evaluate recruitment of RIFA to various livestock feeds. Recruitment was investigated in three areas of Texas with one site in Taylor, Smith, and McLennan counties. Feeds evaluated were a commercial cat food (CAT), previously used by researchers for RIFA recruitment, a calf starter feed, a horse and mule feed, a cow range cube, cottonseed meal, and extruded whole cottonseed (EWC). One-gram samples of each feed were placed into plastic bait cups. At each study, site bait cups were placed in a 6 x 6 Latin square arrangement with two cups of each feed placed on their sides. Bait cups were recovered after 15 and 30 min. After all cups were collected, each site was evaluated for RIFA mound density. To approximate a normal distribution, the natural log of RIFA count per cup was the dependent variable. Data were analyzed through analyses of variance where feed, pasture, feed x pasture, row within pasture, and column within pasture were independent variables. Row within pasture was used as the error term to test pasture differences. Differences were observed for feed (P < 0.001), pasture (P < 0.001), and feed x pasture {P < 0.05) for ant count after 15 (AC15) and 30 min (AC30). Cat food had the highest least squares mean AC15 per cup in four of seven pastures (2.28 to 3.92), and EWC had highest AC15 in the other three (2.56 to 4.00). Extruded whole cottonseed had the highest AC30 in five of seven pastures (4.06 to 5.40), and CAT had the highest count in two pastures (2.64 and 3.14). Across all pastures, for AC15, CAT had higher {P = 0.0197) RIFA recruitment than did EWC (3.14 and 2.67, respectively), with others ranging from 0.86 tol.71 ants per cup. For AC30, EWC averaged 3.79, CAT averaged 3.64 and the rest ranged from 0.96 to 2.32. All pastures had higher ant counts at 30 versus 15 min except two. Ant count after 15 min per pasture ranged from 1.00 to 2.78, whereas AC30 per pasture ranged from 0.69 to 3.09. Density of RIFA mounds across pastures ranged from 395 tol,220/ha, but did not match exactly with AC15 or AC30.
To evaluate the grazing behavior of beef cattle in pastures infested with RIFA, a cattle-tracking GPS collar was developed. The GPS collar was developed as a means to monitor the grazing behavior of cattle within RIFA-infested pastures. Although commercial GPS tracking collars were available at the time of the development of the GPS collars, the cost of $3,000 to $5,000 per collar was prohibitive. In addition, the GPS collars developed provided real-time GPS position data reporting to a computer in a remote location where the position data were stored. Commercially available GPS collars stored position data on board that had to be downloaded once the collar had been retrieved from the animal and were limited by the amount of on-board memory for GPS data storage.
AU RIFA research in the final phase was conducted at the Texas Agricultural Experiment Station (TAES) at McGregor in McLennan County. The objectives of this research were to evaluate the grazing behavior of beef cattle in pastures infested with RIFA. The research was conducted at the Texas Agricultural Experiment Station (TAES) at McGregor in McLennan County. The research was conducted in two phases, with Phase I occurring in July and August, 2001, and Phase II occurring in August and September, 2001. Phase I was conducted using 11 resident TAES commercial Angus cow-calf pairs that were naive to the research pastures (P5 and P6). Cow ages ranged from 9 to 14 yr. Phase II was conducted using 16 crossbred yearling steers that were naive to pastures and RIFA. To monitor the positional location of the cows and steers in both phases of the research, Global Positioning System (GPS) collars were fitted to randomly selected animals. The GPS collars used in Phase I also measured cow head movement with horizontal (HOR) and vertical (VER) motion sensors. Data from HOR and VER were summed to form a total activity (ACT) variable. Additionally both distance (m; DIS) and velocity (m/min; VEL) were calculated for Phases I and II. Chi-square x2 ) and analysis of variance tests were both employed to analyze data. In association with the x2 analysis, a Bonferroni Z simultaneous confidence interval was used to determine cattle preferences for different areas (AREA) within a pasture. Differences {P < 0.0001) were observed for cattle utilization in different areas of the pastures for both Phases I and II and were related to the primary species of forage on offer in those areas. Analysis of variance was used in the analysis of the dependent variables; HOR, VER, ACT, DIS and VEL for Phase I and DIS and VEL for Phase H. The independent variables were date, time-of-day (TOD), and AREA. In Phase I, P5, differences were observed for the TOD effect for HOR (P = 0.0292), VER (P < 0.0001), ACT {P = 0.0464), DIS {P < 0.0001), and VEL {P < 0.0001). For the AREA effect in P5 differences were observed for HOR {P < 0.0001), VER {P < 0.0001), and ACT {P = 0.0002). In Phase I, P6, differences were observed for the TOD effect for HOR {P < 0.0001), VER (P < 0.0001), ACT {P < 0.0001), DIS {P < 0.0001), and VEL {P < 0.0001). The differences observed for the AREA effect in P6 were for VER (P < 0.0001), ACT {P = 0.0003), DIS {P < 0.0001), and VEL {P = 0.0002). In Phase II, P5, differences were observed for DIS for the TOD effect {P < 0.0001) and the AREA effect {P < 0.0001). In P6, differences were observed for DIS and VEL for the TOD effect {P = 0.0312 and P < 0.0001, respectively) and for the AREA effect {P = 0.0003 and P < 0.0001, respectively).